<div id="app">
    <div class="row">

        <div class="col">
            <b-button-group vertical>
                <b-button variant="success">Top</b-button>
                <b-button variant="info">Middle</b-button>
                <b-button variant="primary">Bottom</b-button>
            </b-button-group>
        </div>

        <div class="col">
            <b-button-group>
                <b-button>Left</b-button>
                <b-button>Middle</b-button>
                <b-button>Right</b-button>
            </b-button-group>
        </div>
        <div class="col">
            <b-button-group size="sm">
                <b-button>Left</b-button>
                <b-button>Middle</b-button>
                <b-button>Right</b-button>
            </b-button-group>
        </div>
    </div>
</div>
